See Photos of Meghan Trainor and Her Famous Circle of Friends

Today is Meghan Trainor's 21st birthday! Even though her hit song, "All About That Bass," was only released this year, she's managed to make a ton of new celebrity friends in a short amount of time. The pop star has hung out with everyone from Fifth Harmony to Demi Lovato — and even had the craziest throwback pic from her pre-fame days with Hunter Hayes.

Click through to see more photos of Meghan with her famous friends. Can you believe she knows all these celebs? Send your birthday wishes to her in the comments!